Boom operating trucks are known in the art. One of the main problems with boom operated trucks is the line of sight of the operator. Often when a load is carried at the end of the boom upon a work implement the boom is at a height to interfere with the line of sight of the operator. This creates an unsafe condition. Attempts therefor have been made to correct this problem.
U.S. Pat. No. 30,021 assigned to Loed Corporation and invented by Olson et al discloses a material handling vehicle having a boom which is extensible and pivotally attached to the rear of the vehicle and having a work element thereon. In order for the pivot to be lowered the motor 28 and transmission 108 were lowered as well to provide the vehicle with as low as center of gravity as possible. In traversing a rough terrain having many obstacles and out crops the drive train would be put at risk to damage should the truck attempt to traverse for example a rock laden field. Therefor, although the movement of the motor toward the bottom of the vehicle allows for a lower center gravity of the vehicle and for the lowering of the pivot below the level of the steering wheel of the vehicle, the drive train is still exposed to considerable damage. The cab of the vehicle is offset to one side of the vehicle and a load carrying platform is disposed at the other side of the vehicle, the two members having in between a well having a bottom wherein the extensible boom is disposed.
West German Offenlegungsschaft, 2739537 to the Loed Corporation describes a boom operated truck having a cab disposed on one side and a load carrying compartment disposed on the other, apparently the motor being turned sideways. The vehicle does not include a space or opening between the cab and the motor between substantially vertically extending frame portions.
French Publication 2624842 published in June of 1989, discloses a boom operating truck which has an engine disposed on one side of the center axis of the frame with the cab disposed on the other side. However, the pivot axes is located above the line of sight of an operator. Therefor, the low profile is not achieved even though the machine includes an offset engine.
U.K. Patent Application 2137145 describes a mobile crane or access lift platform. Included in this patent structure of the mobile crane is an drive engine 30 which is offset to one side of the axis of extension of the vehicle. Included with the transmission 36 is a support gear box 38 as best seen in relation to FIG. 3. However, no where within this reference is there described a low profile reach truck being boom operated having all of the attributes of the boom operated truck herein described.
U.S. Pat. No. 4,718,814 discloses a boom operated truck having a work implement which is pivotable with respect to the boom as illustrated in FIG. 3. However, such truck is not a low profile truck that can travel over rough terrain having a lower under carriage extending below the axial of the vehicle.
Canadian Patent 1024107 describes a boom operated truck as illustrated in FIG. 4, having a negative lift capability.
No where within the prior art is there disclosed a boom operated vehicle, the vehicle having an under carriage which is setup at a higher level than the axle of the wheels of the vehicle to insure that the vehicle can cross rough terrain. Most vehicle of the above-mentioned type are for crossing rough terrain in the construction industries involving trenches, rocks and out crops of wood stubs etc. It very likely that the under side of the vehicle can be extensively damaged by hitting a rock. Further, structures provided such as Merlo spa described in patent application WO 89/00972 provides an engine which has a vehicle driven by a hydrostatic transmission. Applicant has reviewed this application and has acquired the brochures of Merlo and has found the drives to be hydrostatic. Although the disclosure does teach the positioning of the cab on one side and the engine on the other it does not state how the power is transferred to the wheels of the vehicle. This is an important consideration when considering a rough terrain vehicle in that the transmission device may end up being damaged. It appears therefor, to the best of Applicants knowledge that Merlo has achieved such by using a hydrostatic transmission and not mechanical drive as Applicant does. Therefor, in hydrostatic transmission pumps and hydraulic motors are provided with hoses which provide the power transformation in a manner known to those skilled in the art. However, at high speeds or high working pressure such as the case with vehicles having a large load bearing capability beyond 6000 PSI requirement of the hoses, the hydrostatic transmission is not desirable. This is because of the high level of maintenance required to fix the pumps and seals of the hydrostatic motor and the hoses which leak and burst. It is much more reliable to provide a mechanical transmission means if the mechanical transmission means can be kept out of the way and up from the risk of damage from rough to rain. Therefor, all of the disadvantages of using the hydrostatic transmission are reduced by the use a mechanical transmission which will be described herein after.
Frame structures provided in the prior art are complex and generally include ferring portions which extend from the bottom frame. A trust or the like must be provided to support the boom of the truck. The trucks may be manufactured to support the boom and to provide for the tremendous loading of the pivot of the boom. Typically reinforcing is required.
The invention provides a massive frame portion which extends vertically and a second portion with extends vertically, the two portion being connected together and providing for sufficient mass and size to both support the required load of a reach truck and provide at least inpart the counter weight ability of the reach truck, as well as providing the opening within which the boom may extend in use to lower the profile of the truck.
It is therefor a primary object of this invention to provide a low profile material handling vehicle including a extensible boom with an opening defined by frame portions of the vehicle, the frame portions of the vehicle providing at least inpart counter weighting means for the vehicle and also providing the vehicle with the ability to traverse rough terrain.
It is a further object of this invention to provide a material handling vehicle including a extensible boom which includes a work implement which is pivotable with respect to the boom and is movable with respect to boom in a direction away from the boom without the need for the boom to be further extended or for the vehicle to be moved or repositioned.
It is still yet a further object of this invention to provide a low profile reach truck which is easy to operate and simple to maintain.
Further and other objects of this invention will become apparent to a man skilled in the art when considering the following summary of the invention and the more detailed description of the preferred embodiments illustrated herein.